In multistage rotary machines such as gas turbine engines, a fluid, e.g., intake air, is compressed in a compressor section and mixed with a fuel in a combustion section. The mixture of air and fuel is ignited in the combustion section to create combustion gases that define a hot working gas that is directed to one or more turbine stages within a turbine section of the engine to produce rotational motion of turbine components. Both the turbine section and the compressor section have stationary or non-rotating components, such as vanes, for example, that cooperate with rotatable components, such as blades, for example, for compressing and expanding the hot working gas. Many components within the machines must be cooled by a cooling fluid to prevent the components from overheating.
Ingestion of hot working gas from a hot gas path into disc cavities in the machines that contain cooling fluid reduces engine performance and efficiency, e.g., by yielding higher disc and blade root temperatures. Ingestion of the working gas from the hot gas path into the disc cavities may also reduce service life and/or cause failure of the components in and around the disc cavities.